Apparatus for performing an open wedge, high tibial osteotomy

ABSTRACT

An apparatus and method for performing an open wedge osteotomy. The apparatus includes devices for forming an open wedge osteotomy in bone, including a keyed-wedge implant. The method includes the steps of forming a cut in a bone, forming a keyhole in the bone surface at the proximal end of the cut, and positioning a keyed wedge-shaped implant into the cut formed into the bone.

REFERENCE TO PENDING PRIOR PATENT APPLICATIONS

This patent application is a division of prior U.S. patent applicationSer. No. 11/396,490, filed Apr. 3, 2006 by Kelly Ammann et al. forMETHOD AND APPARATUS FOR PERFORMING AN OPEN WEDGE, HIGH TIBIALOSTEOTOMY, which in turn:

(i) is a continuation-in-part of pending prior U.S. patent applicationSer. No. 11/047,159, filed Jan. 31, 2005 by Vincent P. Novak for OPENWEDGE OSTEOTOMY SYSTEM AND SURGICAL METHOD;

(ii) is a continuation-in-part of pending prior U.S. patent applicationSer. No. 11/047,551, filed Jan. 31, 2005 by Vincent P. Novak for OPENWEDGE OSTEOTOMY SYSTEM AND SURGICAL METHOD, now U.S. Pat. No. 8,083,746;

(iii) is a continuation-in-part of pending prior U.S. patent applicationSer. No. 11/352,103, filed Feb. 9, 2006 by Vincent P. Novak et al. forMULTI-PART IMPLANT FOR OPEN WEDGE KNEE OSTEOTOMIES, now U.S. Pat. No.8,211,112;

(iv) is a continuation-in-part of pending prior U.S. patent applicationSer. No. 11/350,333, filed Feb. 8, 2006 by Vincent P. Novak et al. forMETHOD AND APPARATUS FOR FORMING A WEDGE-LIKE OPENING IN A BONE FOR ANOPEN WEDGE OSTEOTOMY, now U.S. Pat. No. 8,496,662;

(v) claims the benefit of prior U.S. Provisional Patent Application Ser.No. 60/667,401, filed Apr. 1, 2005 by Kelly Anmann et al. for OPEN WEDGEOSTEOTOMY SYSTEM AND SURGICAL METHOD;

(vi) claims the benefit of prior U.S. Provisional Patent ApplicationSer. No. 60/736,135, filed Nov. 10, 2005 by Kelly Anmann et al. forDESCRIPTION OF A METHOD FOR OBTAINING AN ANTERIOR TO POSTERIOR (AP)SLOPE CORRECTION IN CONJUNCTION WITH A LATERAL TO MEDIAL (LM) CORRECTIONUSING HIGH TIBIAL OSTEOTOMY;

(vii) claims the benefit of prior U.S. Provisional Patent ApplicationSer. No. 60/738,429, filed Nov. 21, 2005 by Vincent P. Novak et al. forMETHOD AND SYSTEM OF INSTRUMENTATION FOR PERFORMING AN OPENING WEDGEOSTEOTOMY; and

(viii) claims the benefit of prior U.S. Provisional Patent ApplicationSer. No. 60/741,313, filed Dec. 1, 2005 by Kelly Ammann et al. forMETHOD AND SYSTEM OF FIXATION FOR PERFORMING AN OPENING WEDGE OSTEOTOMY.

The above-identified patent applications are hereby incorporated hereinby reference.

FIELD OF THE INVENTION

This invention relates to surgical methods and apparatus in general, andmore particularly to surgical methods and apparatus for performing openwedge osteotomies of the knee.

BACKGROUND OF THE INVENTION

Osteotomies of the knee are an important technique for treating kneeosteoarthritis. In essence, knee osteotomies adjust the geometry of theknee joint so as to transfer weight bearing load from arthritic portionsof the joint to the relatively unaffected portions of the joint.

Knee osteotomies are also an important technique for addressing abnormalknee geometries, e.g., due to birth defect, injury, etc.

Most knee osteotomies are designed to modify the geometry of the tibia,so as to adjust the manner in which the load is transferred across theknee joint.

There are essentially two ways in which to adjust the orientation of thetibia: (i) the closed wedge technique; and (ii) the open wedgetechnique.

With the closed wedge technique, a wedge of bone is removed from theupper portion of the tibia, and then the tibia manipulated so as toclose the resulting gap, whereby to reorient the lower portion of thetibia relative to the tibial plateau and hence adjust the manner inwhich load is transferred from the femur to the tibia.

With the open wedge technique, a cut is made into the upper portion ofthe tibia, the tibia is manipulated so as to open a wedge-like openingin the bone, and then the bone is secured in this position (e.g., byscrewing metal plates to the bone or by inserting a wedge-shaped implantinto the opening in the bone), whereby to reorient the lower portion ofthe tibia relative to the tibial plateau and hence adjust the manner inwhich load is transferred from the femur to the tibia.

While both closed wedge osteotomies and open wedge osteotomies providesubstantial benefits to the patient, they are procedurally challengingfor the surgeon. Among other things, with respect to open wedgeosteotomies, it can be difficult to create the wedge-like opening in thebone with the necessary precision and with a minimum of trauma to thesurrounding tissue.

The present invention is directed to open wedge osteotomies of the knee.

SUMMARY OF THE INVENTION

The present invention comprises a novel method and apparatus forperforming an open wedge, high tibial osteotomy. More particularly, thepresent invention comprises the provision and use of a novel method andapparatus for forming an appropriate osteotomy cut into the upperportion of the tibia, manipulating the tibia so as to open anappropriate wedge-like opening in the tibia, and then inserting anappropriate wedge-shaped implant into the wedge-like opening in thetibia, so as to stabilize the tibia with the desired orientation,whereby to reorient the lower portion of the tibia relative to thetibial plateau and hence adjust the manner in which load is transferredfrom the femur to the tibia.

In one form of the present invention, there is provided apparatus forperforming an open wedge, high tibial osteotomy, the apparatuscomprising:

cutting apparatus for forming an osteotomy cut in the tibia, the cuttingapparatus comprising: targeting apparatus for identifying a cuttingplane through the tibia and a boundary line for terminating a cut madealong the cutting plane, wherein the boundary line is located within thetibia, parallel to the anterior-posterior slope of the tibia andparallel to the sagittal plane of the patient.

In another form of the invention, there is provided a method forperforming an open wedge, high tibial osteotomy, the method comprising:

positioning targeting apparatus for identifying a cutting plane throughthe tibia and a boundary line for terminating a cut made along thecutting plane, wherein the boundary line is located within the tibia,parallel to the anterior-posterior slope of the tibia and parallel tothe sagittal plane of the patient;

cutting the bone along the cutting plane, with the cut terminating atthe boundary line;

moving the bone on either side of the cut apart so as to form thewedge-like opening in the bone; and

stabilizing the bone.

In another form of the invention, there is provided apparatus forperforming an open wedge, high tibial osteotomy, the apparatuscomprising:

a wedge-shaped implant for disposition in a wedge-shaped opening createdin the tibia, wherein the wedge-shaped implant comprises at least onekey for disposition in a keyhole formed in the tibia adjacent to thewedge-shaped opening created in the tibia.

In another form of the invention, there is provided a method forperforming an open wedge, high tibial osteotomy, the method comprising:

cutting the bone along a cutting plane, with the cut terminating at aboundary line, and forming at least one keyhole in the tibia adjacent tothe cut;

moving the bone on either side of the cut apart so as to form awedge-like opening in the bone; and

positioning a wedge-shaped implant in the wedge-shaped opening createdin the tibia, wherein the wedge-shaped implant comprises at least onekey, and further wherein the at least one key is disposed in the atleast one keyhole formed in the tibia.

In another form of the invention, there is provided apparatus forperforming an open wedge, high tibial osteotomy, the apparatuscomprising:

cutting apparatus for forming an osteotomy cut in the tibia, the cuttingapparatus comprising: targeting apparatus for identifying a cuttingplane through the tibia and a boundary line for terminating a cut madealong the cutting plane, wherein the boundary line is located within thetibia, parallel to the anterior-posterior slope of the tibia and at aselected angle to the sagittal plane of the patient.

In another form of the invention, there is provided a method forperforming an open wedge, high tibial osteotomy, the method comprising:

positioning targeting apparatus for identifying a cutting plane throughthe tibia and a boundary line for terminating a cut made along thecutting plane, wherein the boundary line is located within the tibia,parallel to the anterior-posterior slope of the tibia and at a selectedangle to the sagittal plane of the patient;

cutting the bone along the cutting plane, with the cut terminating atthe boundary line;

moving the bone on either side of the cut apart so as to form thewedge-like opening in the bone; and

stabilizing the bone.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will bemore fully disclosed or rendered obvious by the following detaileddescription of the preferred embodiments of the invention, which is tobe considered together with the accompanying drawings wherein likenumbers refer to like parts, and further wherein:

FIGS. 1-3 are schematic views showing the formation of a wedge-likeopening in the tibia for an open wedge, high tibial osteotomy, andpositioning of a wedge-shaped implant into the wedge-like opening in thetibia;

FIG. 3A is a schematic view showing selected anatomical planes;

FIGS. 4-9 show the relevant planar surfaces in an open wedge, hightibial osteotomy;

FIGS. 10-30 are schematic views showing a preferred method and apparatusfor foil ling an appropriate osteotomy cut into the upper portion of thetibia, manipulating the tibia so as to open an appropriate wedge-likeopening in the tibia, and then inserting an appropriate wedge-shapedimplant into the wedge-like opening in the tibia;

FIGS. 31-37 are schematic views showing various apex pin dispositionswhich may be used in connection with the open wedge, high tibialosteotomy; and

FIG. 38 is a schematic illustration showing how the disposition of theapex pin may be adjusted in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Overview of an Open Wedge, High Tibial Osteotomy

Looking first at FIGS. 1-3, there is shown a knee joint 5 upon which anopen wedge osteotomy is to be performed. Knee joint 5 generallycomprises a tibia 10 and a femur 15. In accordance with the presentinvention, the open wedge osteotomy is effected by first making a cut 20(FIG. 1) into the upper tibia, and then manipulating the lower portionof the tibia so as to open a wedge-like opening 25 (FIG. 2) in the bone,with the wedge-like opening 25 being configured so as to adjust themanner in which load is transferred from the femur to the tibia. Cut 20and wedge-like opening 25 may be formed in a variety of ways well knownin the art.

Among other things, the present invention provides a new and improvedmethod and apparatus for forming cut 20 and wedge-like opening 25, aswill be discussed in detail below.

Once the desired wedge-like opening 25 has been formed in tibia 10 so asto reconfigure tibia 10 to the desired geometry, the bone may be securedin position in a variety of ways well known in the art (e.g., byscrewing metal plates to the bone or by inserting a wedge-shaped implantinto the opening in the bone), whereby to adjust the manner in whichload is transferred from the femur to the tibia. By way of example, FIG.3 shows a wedge-shaped implant 27 inserted into the wedge-like opening25 formed in the tibia, whereby to stabilize the tibia in itsreconfigured geometry.

Among other things, the present invention also provides a new andimproved wedge-shaped implant, and an associated method and apparatusfor deploying the same into the wedge-shaped opening in the tibia.

Discussion of the Relevant Planar Surfaces in the High Tibial Osteotomyof the Present Invention

In order to appreciate certain aspects of the present invention, it ishelpful to have a thorough understanding of the planar surfaces of thetibia that are relevant in performing the high tibial osteotomy of thepresent invention. Thus, the following discussion presents a geometricdescription of the planar surfaces that are relevant to the open wedge,high tibial osteotomy of the present invention. For the purposes of thepresent discussion, it can sometimes be helpful to make reference toselected anatomical planes, e.g., the coronal plane, the sagittal planeand the transverse plane (FIG. 3A).

Looking now at FIGS. 1-4, for the purposes of the present invention, thetibial plateau 30 may be described as a horizontal (or transverse) planethat extends along the superior surface of tibia 10. For reference, thesagittal plane 32 is also shown in FIG. 4. As seen in FIG. 5, tibialplateau 30 is also perpendicular to the frontal (or coronal) plane 40.The anterior-posterior (A-P) slope is defined by an anterior-posterior(A-P) slope plane 45 that extends along the sloping top surface of thetibia from anterior-to-posterior. Published research has demonstratedthat the anterior-posterior (A-P) slope typically extends at an angle ofapproximately 7.degree. to 11.degree. to the tibial plateau 30; however,the specific angle may vary from individual to individual.

Looking next at FIG. 6, for the high tibial osteotomy of the presentinvention, it is generally desirable to stay about 2 cm inferior to theA-P slope plane 45. This offset can be referred to as the A-P offsetplane 50.

As seen in FIG. 7, the lateral aspect and cut depth may be defined by alateral aspect plane 55 and a cut depth plane 60, with the cut depthbeing about 1 cm medial to the lateral aspect of the tibia.

Looking next at FIG. 8, the osteotomy cut plane 65 (when seen from thedirect frontal view of FIG. 8) is formed by a plane that is rotated awayfrom the A-P offset plane 50 through an axis formed by the intersectionof the cut depth plane 60 and the A-P offset plane 50. The degree ofrotation is selected so as to be sufficient to place the entry of theosteotomy cut plane 65 at the medial neck 66 (FIG. 8) of the tibia. Itshould be noted that the A-P offset plane 50 and the osteotomy cut plane65 are “tilted” slightly from anterior to posterior (but not seen in thedirect frontal view of FIG. 8), since the A-P offset plane 50 and theosteotomy cut plane 65 follow the tilt of the A-P slope plane 45 (FIG.6). The intersection of the A-P offset plane 50 and the cut depth plane60 forms an axis 70 which, in accordance with the present invention,defines the lateral limit of the osteotomy cut. In other words, axis 70defines a line through the tibia which is (i) parallel to A-P slopeplane 45, and (ii) contained within osteotomy cut plane 65. Furthermore,in accordance with the present invention, axis 70 is used to define thelateral limit of the osteotomy cut which is to be made into the tibia.

As seen in FIG. 9, the direct view of the osteotomy plane is a directview in line with the osteotomy. This view is tilted downward (e.g., atapproximately 7.degree.) from the direct frontal view. Again, the angleof tilt downward is equal to the A-P slope. In other words, with thepresent invention, the osteotomy cut plane 65 extends parallel to theA-P slope plane 45 (in the anterior-to-posterior direction, although notin the medial-to-lateral direction), and typically slopes downward(e.g., at an angle of 7-11.degree.) when viewed in theanterior-to-posterior direction. Furthermore, with the presentinvention, the axis 70 (which defines the lateral limit to the osteotomycut) is contained within the osteotomy cut plane 65.

Novel Method and Apparatus for Performing the Open Wedge, High TibialOsteotomy of the Present Invention

In one preferred embodiment of the present invention, there is provideda novel osteotomy system which comprises instrumentation for use inmaking precise and repeatable osteotomy cuts for use in open wedge, hightibial osteotomies, preferably using an antero-medial approach. Thenovel osteotomy system generally comprises a positioning guide 100 (FIG.16), a slope guide 200 (FIG. 11), an apex pin 300 (FIG. 16), a keyholedrill guide 400 (FIG. 18), a posterior protector 500 (FIG. 20), and acutting guide 600 (FIG. 20), as will hereinafter be discussed in furtherdetail.

The novel osteotomy system preferably also comprises a novel openingjack 700 (FIG. 22) for opening the cut in the tibia so as to form thewedge-like opening in the tibia, as will also hereinafter be discussedin further detail.

And the novel osteotomy system preferably also includes a novel implant800 (FIG. 24) for positioning in the wedge-like opening in the tibia soas to stabilize the tibia in its corrected configuration, as will alsohereinafter be discussed in further detail.

In a preferred form of the invention, the novel osteotomy system isconfigured so that:

(i) the axis 70 formed at the lateral limit of the osteotomy cut (whichforms the lateral bony hinge when the osteotomy cut is opened) isparallel to the A-P tibial slope;

(ii) the axis of the lateral bony hinge created by the osteotomy lies ina plane that is perpendicular to the frontal (i.e., coronal) plane; and

(iii) when the osteotomy is completed and the wedge is opened, thedistal (i.e., lower) tibia is rotated about the bony hinge so as tosubstantially maintain, in anatomical alignment, the A-P slope and thefrontal plane.

In a preferred form of the invention, the novel osteotomy system is alsoconfigured so that:

(iv) the osteotomy can be performed less invasively; and

(v) the osteotomy can be performed with minimum incising of soft tissuesuch as the medial collateral ligament, the lateral collateral ligament,and the hamstrings.

In one preferred form of the invention, the novel osteotomy system isconstructed and used as follows:

1. A vertical incision is first made on the antero-medial portion of theknee, approximately 1 cm from the medial edge of the patellar tendon,with the incision beginning approximately 2.5-3 cm inferior to the jointline, and extending approximately 6-10 cm in length.

2. The soft tissue between the patellar tendon and the proximal tibiasurface is then dissected in order to make a small tunnel-like openingbeneath the patellar tendon, just above the patellar tendon's insertionto the proximal tibia.

3. Looking now at FIG. 10, an assembly comprising position guide 100(FIGS. 10 and 16), slope guide 200 (FIGS. 10 and 11) and an introducer105 (FIGS. 10 and 11) is advanced to the surgical site. Preferably theassembly of position guide 100, slope guide 200 and introducer 105 ispre-assembled prior to opening the skin. The assembly is assembled bymounting slope guide 200 to position guide 100 and then mountingintroducer 105 to slope guide 200 and position guide 100 using a screw115 (FIG. 10) passing through slope guide 200 and received in a threadedbore 120 formed in position guide 100.

In one preferred form of the invention, slope guide 200 may comprise twoseparate elements secured together, a base 210 and a guide element 215connected by pins 205, with base 210 being formed out of aradio-translucent material (e.g., plastic) and with guide element 215being formed out of a radio-opaque material (e.g., stainless steel),whereby guide element 215 will be visible under fluoroscopy and base 210will be effectively invisible under fluoroscopy, as will hereinafter bediscussed. In one preferred form of the invention, introducer 105 maycomprise an arm 125 and a handle 130. Arm 125 and handle 130 may beformed as two separate elements secured together, or arm 125 and handle130 may be formed as a singular construction.

4. Next, the foregoing assembly is maneuvered so that a tibial tuberclelocating tab 135 (FIGS. 10 and 16) of position guide 100 is insertedbetween the patellar tendon (not shown) and the tibia, and so thattibial tubercle locating tab 135 is set against the tibial tubercle. Inthis way, the tibial tubercle provides a rough alignment guide foraligning position guide 100 with the tibia.

5. Using a lateral fluoroscope view, taken from the medial side at thelevel of the tibial plateau, the assembly is aligned so that theunderside surface 220 of guide element 215 of slope guide 200 (FIG. 11)is aligned with the top of the medial condyle 75 of the tibia. See FIG.11. Alternatively, if the surgeon prefers to shift the osteotomyslightly distally on the tibia, the top edge 225 of guide element 215 ofslope guide 200 can be aligned with medial condyle 75, offsetting theosteotomy a fixed distance distally (e.g., 3 mm).

By forming the guide element 215 of slope guide 200 out of aradio-opaque material and by forming the base 210 of slope guide 200 outof a radio-translucent material, base 210 will be effectively invisibleunder fluoroscopy and guide element 215 will stand out in clear reliefagainst the bone.

It should be noted that guide element 215 of slope guide 200 ispreferably formed with a “Z shape” (FIGS. 10 and 11A) so as to provideadditional functionality. More particularly, by forming guide element215 with a “Z shape”, several significant advantages are obtained.First, this construction permits guide element 215 to wrap around theperimeter of the tibia. Second, the “Z shape” of guide element 215 alsooperates to indicate if the slope guide is not vertically aligned withthe level of the fluoroscope. More particularly, if slope guide 200 isnot vertically aligned with the level of the fluoroscope, the “Z shape”of guide element 215 will appear as a jagged or zig-zag shape on thefluoroscope (FIG. 11B). However, if guide element 215 is verticallyaligned with the level of the fluoroscope, then the guide element willappear as a straight line on the fluoroscope (FIGS. 11 and 11C). Thisvertical alignment is important, since it enables alignment of slopeguide 200 (and hence position guide 100) with the medial condyle, i.e.,the A-P slope plane.

7. The assembly is then maneuvered so that the medial locating pin 140(FIGS. 10, 11 and 16), preferably formed as a pin although it could alsobe formed as a tab, fin, etc., is located against the medial aspect 80of the tibia (FIG. 16). As further adjustments in position are made,medial locating pin 140 is held in contact with the medial aspect of thetibia, thus ensuring proper alignment of the instrumentation. Mediallocating pin 140 references the medial aspect of the tibia, thus settingthe distance from the medial aspect of the tibia to the apex pin 300(FIG. 10), as will hereinafter be discussed. This reference distance isused in conjunction with the sizing of the osteotomy implant 27 (FIG. 3)to ensure a proper tibial reconstruction, i.e., the distance from themedial aspect of the tibia to the center of apex pin 300 is designed tocorrespond to the distance from the medial aspect of the implant to thevertex of the wedge angle of the implant.

In another form of the invention, the reference distance may be thedistance from the medial aspect of the tibia to a neutral axis ofrotation in the bony hinge, which could be estimated by calculation. Inthis case, the distance from the medial aspect of the tibia to theneutral axis of the bony hinge would correspond to the distance from themedial aspect of the implant to the vertex of the wedge angle of theimplant.

8. The assembly is then rotated around the primary tibial anatomicalaxis, by sliding introducer handle 130 in side-to-side motion, such thatthe instrumentation is aligned perpendicular to the frontal (coronal)plane, i.e., so that introducer 105 and apex pin 300 (see below) willextend parallel to the sagittal plane of the patient. To this end, slopeguide 200 is provided with a ball 230 and a groove 235. With thefluoroscope arranged so that it is set in the lateral mode, with theimage being taken from the medial side at the level of the tibialplateau (see FIG. 11), the assembly is maneuvered until ball 230 iscentered in groove 235 (FIG. 11). When this occurs, the system isaligned with the sagittal plane (i.e., position guide 100 is disposed sothat apex pin 300 will extend perpendicular to the frontal plane, aswill hereinafter be discussed).

9. Thus, when slope guide 200 is aligned with the medial condyle 75, andwhen ball 230 is aligned with groove 235, the system is aligned with (i)the A-P slope, and (ii) the sagittal plane. In other words, when slopeguide 200 is aligned with medial condyle 75, and when ball 230 isaligned with groove 235, the instrumentation is positioned so that apexpin 300 (see below) will be aligned with both the A-P slope and thesagittal plane, as will hereinafter be discussed.

10. With all of the previous adjustments in place, the positions of (i)tibial tubercle locating tab 135, (ii) slope guide 200, (iii) mediallocating pin 140, and (iv) the ball and groove sights 230, 235 areverified. With all positions confirmed, the frontal pin 145 (FIG. 16)and the antero-medial (AM) pin 150 (FIG. 16) are inserted throughposition guide 100 and into the tibia. This secures position guide 100to the tibia with the desired alignment.

11. Next, apex pin 300 is inserted through position guide 100 and intothe tibia. An apex aimer 155 (FIGS. 14 and 16) serves to guide apex pin300 into the tibia with the proper orientation, i.e., so that apex pin300 is positioned along the axis 70 formed at the lateral limit to theosteotomy cut, with apex pin 300 extending parallel to the A-P slope,perpendicular to the coronal plane, and within cutting plane 65. As aresult, apex pin 300 can serve as the lateral stop for the osteotomysaw, whereby to clearly define the perimeter of the bony hinge, as willhereinafter be discussed. Apex pin 300 may be tapped or drilled intovirgin bone, or it may be received in a pre-drilled hole (e.g., formedusing apex aimer 155). A thumbscrew 160 (FIG. 16) may be used to secureapex pin 300 to position guide 100.

Apex pin 300 may be cylindrical in shape.

Alternatively, apex pin 300 may have a flat 305 (FIGS. 12 and 13) formedthereon to promote a complete cut-through of the osteotomy. Where apexpin 300 is provided with a distinct flat 305, it is preferably providedwith a counterpart flat 310 (FIGS. 12 and 13), so that when apex pin 300is in place and thumbscrew 160 is tightened against flat 310, theaforementioned flat 305 will be aligned with the osteotomy cut, wherebyto ensure that the osteotomy blade cuts completely through the bone toreach the apex pin. See FIG. 13.

In another version of this construction (not shown), the flats 305, 310may be diametrically opposed to one another, with thumbscrew 160 alsobeing aligned with the osteotomy cut to make insertion of apex pin 300less prone to error.

And in another embodiment of the present invention, apex pin 300 may benecked down to a smaller diameter in the area of the osteotomy. As aresult of this construction, a slight relief area exists to accommodatethe saw blade so as to help promote a complete cut-through, but does notrequire any specific orientation of the apex pin with respect to theosteotomy plane, as is the case where the apex pin is formed withdistinct flats.

And in another version of the present invention, apex aimer 155 may beused with a guide sleeve 160 and a small-diameter guide pin 165 in orderto first check the position of the small-diameter guide pin 165 relativeto the desired axis for the apex pin, before thereafter deploying thelarger-diameter apex pin 300. See FIG. 14. In this respect, it will beappreciated that repositioning a misdirected small-diameter guide pin165 is easier and less traumatic to the host bone than repositioning amisdirected larger-diameter apex pin 300.

As seen in FIG. 15, tibial tubercle locating tab 135 is preferably sizedso that it also functions as an anterior protector, by providing aprotective shield between the oscillating saw blade (to be used later inthe procedure to form the osteotomy cut 20) and the anterior soft tissuestructures, e.g., the patellar tendon.

12. By virtue of the foregoing, it will be seen that apex pin 300 isdeployed in the patient's tibia so that the apex pin extends (i)parallel to the A-P slope of the tibia, and (ii) parallel to thesagittal plane of the patient. As a result, when the osteotomy cut issubsequently formed in the bone (see below) by cutting along theosteotomy cut plane until the apex pin is engaged, so that the perimeterof the bony hinge is defined by the location of the apex pin, the bonyhinge will extend (i) parallel to the A-P slope of the tibia, and (ii)parallel to the sagittal plane of the patient. By ensuring that apex pin300 is set in this fashion, and hence ensuring that the bony hinge is socreated, the final configuration of the tibia can be properly regulatedwhen the bone cut is thereafter opened so as to form the open wedgeosteotomy.

13. Once apex pin 300 has been properly positioned in the bone, slopeguide 200 and introducer 105 are removed, leaving position guide 100properly aligned on, and secured to, the tibia, and apex pin 300properly deployed into the tibia (i.e., with apex pin 300 extendingparallel to the A-P slope and parallel to the sagittal plane of thepatient). See FIG. 16. The size of position guide 100 and the associatedinstrumentation is used to prepare the osteotomy to fit the particularimplant sizing of small, medium or large. More particularly, the mediallocating pin 140, the size of position guide 100, and apex pin 300 allcombine to implement the implant sizing scheme. As seen in FIG. 17,medial locating pin 140, position guide 100 and apex pin 300 combine toprovide a known, fixed distance from the medial aspect of the tibia tothe apex pin. The size of the planned osteotomy is then set, allowing aspecifically-sized implant (e.g., small, medium or large) to nominallyfit between the medial aspect and the apex pin.

In the embodiment shown in FIG. 17, there is a known lateral offsetbetween medial locating pin 140 and the entry point of the osteotomy.The implant size is reduced slightly to factor in this offset distanceso as to yield a proper fit.

In an alternative construction, medial locating pin 140 may be perfectlyaligned with the entry point of the planned osteotomy (not shown).

14. Looking next at FIG. 18, keyhole drill guide 400 is then attached toposition guide 100 by passing keyhole drill guide 400 over frontal pin145 and apex aimer 155. Keyhole drill guide 400 is then secured in thisposition with thumbscrew 405. At this point, a distal pin 410 isinserted through keyhole drill guide 400 and into the tibia. Distal pin410 further secures the instrumentation to the tibia. Next, a surfacelocator pin 415 is inserted through keyhole drill guide 400. Surfacelocator pin 415 slides through keyhole drill guide 400 until the distaltip of surface locator pin 415 contacts the surface of the tibia. Forthe purposes of the present invention, this surface may be referred toas the “antero-medial surface” or the “A-M surface”, which is theanatomical surface of the tibia corresponding to the antero-medialapproach of the osteotomy. When surface locator pin 415 contacts the A-Msurface, the surface locator pin can act as an indicator as to thelocation of the A-M surface. This information can then be used to setthe depth of the keyholes to be formed in the tibia (see below) for animproved implant fit.

Next, an end mill 420 is inserted into the distal hole 425 (i.e., thebottom hole 425) of keyhole drill guide 400 and drilled until a stopflange 430 on end mill 420 contacts the proximal end of surface locatorpin 415, whereby to form the distal keyhole 85 (FIG. 21) in the tibia.The drilling procedure is then repeated for the proximal hole 435 (i.e.,the top hole 435), whereby to form the proximal keyhole 90 (FIG. 21) inthe tibia. While it is possible to drill the proximal keyhole before thedistal keyhole, it is generally preferable to drill the distal keyholefirst. This is because drilling the distal keyhole before the proximalkeyhole reduces the possibility that the sloping nature of the bone willcause a later-drilled keyhole to slip into an earlier-drilled keyhole.It should be appreciated that keyhole drill guide 400 is configured sothat distal hole 425 and proximal hole 435 will overlap the osteotomycutting plane 65 to some extent (FIG. 21), so that when osteotomy cut 20is thereafter formed and the tibia subsequently opened so as to createthe wedge-like opening 25, distal keyhole 85 and proximal keyhole 90will overlap, and communicate with, the wedge-like opening 25 (FIG. 29).

15. Once the two implant keyholes have been drilled into the tibia, endmill 420 is removed, thumbscrew 405 is loosened, and then keyhole drillguide 400 is removed.

16. Next, and looking now at FIG. 19, posterior protector 500 isattached to an introducer 505 with a thumbscrew 510. The far tip 515(FIGS. 19 and 21) of posterior protector 500 is inserted into theincision. Posterior protector 500 is preferably formed out of a somewhatflexible material so as to allow the posterior protector to flexslightly to allow easier insertion into the incision and to conform tothe shape of the posterior cortex. See FIG. 19. Posterior protector 500is inserted by gradually sliding it around the posterior cortex of thetibia until far tip 515 of posterior protector 500 substantially crossesthe axis of, and in some cases actually engages, apex pin 300 (FIG. 21).Posterior protector 500 preferably comprises a stiff curved portion 520proximal to flexible tip 515. Once posterior protector 500 has beenproperly deployed, the thumbscrew 510 is unscrewed, and introducerhandle 505 is removed.

17. Looking next at FIG. 20, cutting guide 600 is then attached toposition guide 100 and secured in place using cutting guide thumbscrew605. Cutting guide 600 comprises alignment rods 610 that extend from thecutting guide into the pre-drilled keyholes 85, 90 (FIG. 21) to assistwith cutting alignment. More particularly, alignment rods 610 ensureproper alignment between cutting guide 600, its cutting slot 615 (FIGS.20 and 21) and the pre-drilled keyholes 85, 90 previously formed in thetibia with end mill 420 and, ultimately, ensure the desired fit betweenthe implant and the tibia.

Then, posterior protector 500 is attached to cutting guide 600 usingthumbscrew 620 (FIG. 20).

At this point, the instrumentation is ready to form the osteotomy cut,with cutting slot 615 of cutting guide 600 properly aligned with theosteotomy cut plane, apex pin 300 properly positioned at the far(lateral) limit of the osteotomy cut, tibial tubercle locating tab 135forming a protective shield for the patellar tendon, and with posteriorprotector 500 forming a protective shield for the vascular andneurological structures at the back of the knee. In this respect itshould be appreciated that cutting guide 600 is sized and shaped, andcutting slot 615 is positioned, so that, in addition to being alignedwith the apex pin 300, the entry point of the cutting plane into thetibia is located at an appropriate location on the tibia's medial neck66.

18. Next, a saw blade 625 (attached to an oscillating saw, not shown) isinserted into cutting slot 615 of cutting guide 600. The osteotomy cutis then made by plunging the oscillating saw blade through cutting slot615 and into the bone (FIG. 20). The saw blade will cut completelythrough the medial and posterior cortices. The saw is operated until sawblade 625 contacts posterior protector 500 and apex pin 300. As the sawblade cuts through the tibia, it is constrained by cutting slot 615,apex pin 300 and posterior protector 500, so that the saw blade may onlycut bone along the osteotomy plane, up to but not beyond the desiredlocation of the bony hinge, and does not cut soft tissue. Duringcutting, tibial tubercle locating tab 135 also ensures that the sawblade will not inadvertently cut the patellar tendon.

After saw blade 625 forms the desired osteotomy cut 20 along the cuttingplane, the saw blade is removed, and a hand osteotome (not shown) of thesort well know in the art is inserted through cutting slot 615 and intothe osteotomy cut 20, and then the cut is completed through theposterior cortical bone near apex pin 300 and posterior protector 500.Then the hand osteotome is removed.

At this point the osteotomy cut 20 has been completed, with theosteotomy cut terminating on the lateral side at apex pin 300, so thatthe bony hinge is properly positioned at the desired location, i.e.,parallel to the A-P slope and perpendicular to the coronal plane.

Next, thumbscrew 620 is loosened and posterior protector 500 removed.Then thumbscrew 605 is loosened and cutting guide 600 is removed.

At this point, the desired osteotomy cut 20 has been formed in thetibia, with keyholes 85 and 90 formed below and above, respectively, theosteotomy cut.

In order to complete the procedure, the bone must now be opened so as toreconfigure the tibia to the desired geometry, and then the tibiastabilized with the desired configuration, e.g., by inserting awedge-shaped implant 27 into wedge-like opening 25.

19. Looking next at FIG. 22, opening jack 700 is assembled onto theinstrumentation by receiving frontal pin 145 in a hole 705 formed injack arm 710, by receiving apex aimer 155 in another hole 715 formed injack arm 710 and jack arm 725, and by receiving distal pin 410 in a slot720 formed in jack arm 725. Opening jack 700 is secured to positionguide 100 with a thumbscrew 730.

Once opening jack 700 is in place, the jack is opened by rotating jackscrew 735. This causes jack arm 725 to pivot about apex aimer 155 so asto open the jack and thereby open the desired wedge-like opening 25 inthe tibia. See FIG. 23. Preferably the patient's lower leg ismanipulated as jack screw 735 is turned so as to assist opening of thebone. As the wedge-like opening 25 is created in the bone, the tibiawill be reoriented in a highly controlled manner, due to the fact thatthe bony hinge will be precisely positioned at axis 70 through the useof apex pin 300, i.e., the bony hinge will extend parallel to the A-Pslope and parallel to the sagittal plane. Furthermore, as the wedge-likeopening 25 is created in the bone, the risk of bone cracking will beminimized, due to the fact that apex pin 300 forms an oversized hole 95(FIGS. 23A and 27) at the lateral end of the bone cut, i.e., “oversized”relative to the thickness of the osteotomy cut, whereby to reduce theoccurrence of stress risers and the like.

20. Then, with opening jack 700 still in place, an implant is positionedin the wedge-like opening 25. If desired, the implant may be a “generic”implant such as the implant 27 shown in FIG. 3. More preferably,however, and looking now at FIG. 24, there is shown a wedge-shapedimplant 800 formed in accordance with the present invention.Wedge-shaped implant 800 is characterized by a wedge-like side profileconfigured to match the geometry of the wedge-like opening 25.Preferably, wedge-shaped implant 800 is also formed so as to have aU-shaped top profile, such that it can form a barrier about theperimeter of the wedge-like opening 25, whereby to constrain graftmaterial (e.g., bone paste, bone cement, etc.) which may be positionedwithin the interior of the wedge-like opening 25. In one preferred formof the present invention, wedge-shaped implant 800 is formed so as tohave an asymmetric configuration when viewed in a top view, so as tomate with the geometry of the tibia when the implant is positioned usingan antero-medial approach. Wedge-shaped implant 800 may be formed out ofabsorbable material or non-absorbable material, as desired.

In one preferred form of the invention, and looking now at FIGS. 25 and26, implant 800 preferably comprises a three-part assembly, comprisingposterior graft containment arm (GCA) 805, a base 810 and an anteriorgraft containment arm (GCA) 815. The individual components of implant800 may each be formed out of absorbable material and/or non-absorbablematerial, as desired. Furthermore, where one or more of the implantcomponents is formed out of an absorbable material, the absorptioncharacteristics of the material may vary as desired. By way of examplebut not limitation, base 810 may be formed out of a relativelyslowly-absorbing material, while posterior graft containment arm (GCA)805 and anterior graft containment arm (GCA) 815 may be formed out of arelatively faster-absorbing material. Base 810 preferably comprises apair of keys 820, 825.

In one preferred form of the invention, implant 800 is formed so thatposterior graft containment arm (GCA) 805 has a generally wedge-shapedprofile including an engagement seat 826 comprising an alignment post827, and an introducer hole 828 opening on the antero-medial side of thecomponent for engagement with introducer 845 (see below). Astrengthening rib 829 is preferably provided as shown. Additionally,raised points or dimples 831 may be provided to help fix GCA 805 to thebone. An alignment tab 832 is provided for extension into upper keyhole90 (FIG. 29) when GCA 805 is positioned in the wedge-shaped opening 25.

And in one preferred form of the invention, base 805 is formed so thatits keys 820, 825 each includes a tapered axial bore 833, 834,respectively, with the keys being slotted longitudinally so as to permitexpansion of the keys when screws 865 are thereafter deployed in thetapered axial bores. External ribs 836 may be provided on the outersurfaces of keys 820, 825 so as to help fix keys 820, 825 in keyholes85, 90, respectively, as will hereafter be discussed in further detail.An alignment mechanism (not shown) is provided for mating with alignmentpost 827 of GCA 805.

Anterior graft containment arm (GCA) 815 also comprises a generallywedge-shaped profile, and an alignment tab 834 is provided for extensioninto lower keyhole 85 when GCA 815 is positioned in the wedge-shapedopening 25.

Horseshoe implant 800 is preferably assembled in situ.

More particularly, a pre-assembled assembly comprising posterior graftcontainment arm (GCA) 805, an implant trial base 830 and two guidesleeves 835, 840 are first inserted into wedge-like opening 25 in thebone using an introducer 845. See FIGS. 27 and 28.

Next, a drill sleeve 850 and a drill 855 are inserted into guide sleeve840 (FIG. 27). An upper hole is drilled into the tibia with the drill.The drilling procedure is then repeated for guide sleeve 835 so as tocreate a lower hole. Then drill sleeve 850 and drill 855 are removedfrom the surgical site. Next, a tap 860 is inserted into guide sleeve840 and the upper hole is tapped. See FIG. 28. Then the tap is insertedinto guide sleeve 835 and the lower hole is tapped. Then tap 860 isremoved from the surgical site.

21. Next, posterior graft containment arm (GCA) 805 is released fromintroducer 845, and then introducer 845 and implant trial base 830 areremoved.

22. Then, if desired, graft material is packed into the osteotomyopening.

23. Next, anterior graft containment arm (GCA) 815 is placed into theosteotomy opening and aligned with the prepared implant holes. See FIG.29. If necessary, jack screw 735 is rotated as needed so as tofacilitate insertion of anterior GCA 815.

24. Then implant base 810 is inserted into the prepared osteotomy, withkeys 820 and 825 seated in tibial holes 85 and 90, respectively. SeeFIG. 29. Keys 820 and 825, seating in tibial holes 85 and 90, helpensure a precise fit of the implant to the bone. As this is done, jackscrew 735 is adjusted as necessary to facilitate insertion of the baseinto the osteotomy. Then jack screw 735 is tightened slightly to ensurethat the implant components are fully seated into the osteotomy wedge.Next, fixation screws 865 are inserted through keys 820 and 825 in base810 and into the tapped holes in the tibia, and tightened into place.See FIG. 30. Finally, opening jack 700, position guide 100, apex pin300, distal pin 410, frontal pin 145 and A-M pin 150 are removed fromthe surgical site, and the incision closed.

Anterio-Lateral Osteotomies

In the foregoing description, the present invention is discussed in thecontext of performing an open wedge osteotomy using an antero-medialapproach. Of course, it should be appreciated that the present inventionmay also be used in antero-lateral approaches, or other approaches whichwill be well known to those skilled in the art.

Method for Obtaining an Anterior-Posterior (A-P) Slope Correction inConjunction with a Lateral-Medial (L-M) Correction in a High TibialOsteotomy

In the foregoing description, there was disclosed an approach foreffecting a high tibial osteotomy in which the surgeon determines theanterior-posterior (A-P) slope of the tibia and determines the properorientation of the osteotomy in relation to the frontal (i.e., coronal)plane of the tibia. After this is done, the surgeon places an apex pininto the tibia so as to precisely define the lateral limit of theosteotomy cut and hence the bony hinge of the osteotomy. The foregoingdiscussion identifies the importance of setting the apex pin parallel tothe A-P tibial slope and perpendicular to the frontal (i.e., coronal)plane. See FIG. 31 which shows the apex pin perpendicular to the coronalplane, and FIG. 32 which shows the axis of the apex pin parallel to theA-P slope. Such an approach is important to prevent inadvertent orunintended changes to the A-P tibial slope as the alignment correction(and the opening of the osteotomy) is executed. However, there may besituations in which the surgeon may deliberately wish to introduce anA-P slope change into the tibia, e.g., such as when resolving kneeinstability or knee ligament laxity.

The following disclosure describes an approach which allows the surgeonto make a quantifiable change to the A-P tibial slope. This approachessentially involves rotating the axis of the apex pin about thelongitudinal axis of the tibia to a prescribed angle relative to thesagittal plane. This is in contrast to the preferred approach disclosedabove, in which the axis of the apex pin is parallel to the sagittalplane.

More particularly, FIG. 33 shows the axis of the apex pin disposedparallel to the sagittal plane. As noted previously, this orientationproduces a lateral-medial (L-M) correction without affecting the A-Pslope, since the inserted apex pin is parallel to the A-P slope.

Looking now at FIG. 34, the axis of the apex pin is shown rotated in theposterior direction (i.e., counter-clockwise when seen from the top viewof FIG. 34). This alternative orientation of the apex pin produces anincreased A-P slope with a corresponding adjustment of the L-M slope.The resulting L-M and A-P slope corrections are a function of the totalcorrection angle, i.e., the total amount that the axis of the apex pinis rotated relative to the sagittal plane.

Looking now at FIG. 35, the axis of the apex pin is shown rotated in theanterior direction (i.e., clockwise when seen from the top view of FIG.35). This alternative orientation of the apex pin produces a decreasedA-P slope with a corresponding adjustment of the L-M slope. Again, theresulting L-M and A-P slope corrections are a function of the totalcorrection angle, i.e., the total amount that the axis of the apex pinis rotated relative to the sagittal plane.

For discussion purposes, it can be assumed that there are no surgicallimitations on the orientation of the apex pin. This allows theinspection of extreme orientations for the purposes of illustrating theoperative concepts. From a surgical perspective, however, there arepractical limitations to how far the apex pin can be rotated relative tothe “standard” position (i.e., parallel to the sagittal plane). However,the following examples are valid for illustration purposes.

Looking now at FIG. 36, it becomes clear that if the apex pin isoriented posteriorly and parallel to the frontal (coronal) plane, theopening wedge osteotomy produces only A-P slope increases with no effecton the L-M slope.

Similarly, and looking now at FIG. 37, an apex pin that is orientedanteriorly and parallel to the frontal (coronal) plane, produces onlyA-P slope decreases with no effect on the L-M slope.

It is clear from FIGS. 36 and 37 that, using this method, andinterpolating between the extreme orientations, it is possible to obtainany combination of L-M slope, and either A-P slope increase and/or A-Pslope decrease, by reorienting the apex pin relative to the sagittalplane.

An apex pin that is oriented 45.degree. from the sagittal plane willnecessarily produce equal L-M and A-P corrections for a given totalcorrection angle. A 45.degree. posterior orientation produces equalangle L-M increase and A-P increase. A 45.degree. anterior orientationproduces equal angle L-M increase and A-P decrease.

Furthermore, it can be shown that an apex pin located near the medialcortex instead of the lateral cortex will produce L-M slope changes inthe opposite direction. This may be used for correcting a valgusmalalignment.

Various constructions may be used to orient apex pin 300 with thedesired angle relative to the sagittal plane. By way of example but notlimitation, FIG. 38 shows how apex aimer 155 may be slidably mounted toa curved boom B so that the angle of apex pin may be adjusted relativeto the sagittal plane. Other constructions will be apparent to thoseskilled in the art in view of the present disclosure.

MODIFICATIONS

It will be understood that many changes in the details, materials, stepsand arrangements of parts, which have been herein described andillustrated in order to explain the nature of the invention, may be madeby those skilled in the art without departing from the principles andscope of the present invention.

What is claimed is:
 1. Apparatus for performing an open wedge, hightibial osteotomy, the apparatus comprising: cutting apparatus forforming an osteotomy cut in the tibia, the cutting apparatus comprising:targeting apparatus for identifying a cutting plane through the tibiaand a boundary line for terminating a cut made along the cutting plane,wherein the boundary line is located within the tibia, parallel to theanterior-posterior slope of the tibia and parallel to the sagittal planeof the patient.
 2. Apparatus according to claim 1 wherein the targetingapparatus is configured so as to form an oversized hole along theboundary line, whereby to minimize the occurrence of stress riserswithin the tibia when the bone on either side of the cut is moved apartso as to form the wedge-like opening in the tibia.
 3. Apparatusaccording to claim 1 wherein the targeting apparatus further comprisesan apex pin for disposition along the boundary line, wherein the apexpin provides a positive stop at the boundary line for limiting cuttingalong the cutting plane.
 4. Apparatus according to claim 3 wherein theapex pin is sized so as to form an oversized hole along the boundaryline, whereby to minimize the occurrence of stress risers within thetibia when the bone on either side of the cut is moved apart so as toform the wedge-like opening in the tibia.
 5. Apparatus according toclaim 3 wherein the apex pin comprises a flat at the positive stop. 6.Apparatus according to claim 3 wherein the apex pin is necked down atthe positive stop.
 7. Apparatus according to claim 1 wherein thetargeting apparatus is configured so that the cutting approach is in agenerally antero-medial direction.
 8. Apparatus according to claim 1wherein the targeting apparatus comprises a slope guide for determiningthe anterior-posterior slope of the tibia whereby to determine thelocation of the boundary line.
 9. Apparatus according to claim 8 whereinthe slope guide comprises an elongated body having a non-circularcross-section.
 10. Apparatus according to claim 1 wherein the targetingapparatus comprises an alignment mechanism for determining the coronalplane and hence the sagittal plane, whereby to determine the location ofthe boundary line.
 11. Apparatus according to claim 1 wherein thecutting apparatus comprises a positioning guide and a cutting guide;wherein the positioning guide is configured for attachment to the tibiaso as to establish the cutting plane and the boundary line relative tothe tibia; and wherein the cutting guide is configured for attachment tothe positioning guide so as to align a cutting slot with the cuttingplane.
 12. Apparatus according to claim 11 wherein the cutting guide isconfigured so that the cutting approach is in a generally antero-medialdirection.
 13. Apparatus according to claim 11 wherein the cuttingapparatus comprises a drill guide for forming at least one keyhole inthe tibia adjacent to the cutting plane.
 14. Apparatus according toclaim 13 wherein the cutting apparatus is configured so that the atleast one keyhole overlays the cutting plane.
 15. Apparatus according toclaim 1 wherein the apparatus further comprises a jack for opening thecut made along the cutting plane so as to form a wedge-like openingwithin the bone.
 16. Apparatus according to claim 15 wherein thetargeting apparatus further comprises an apex pin for disposition alongthe boundary line, and further wherein the jack is configured formounting on the apex pin.
 17. Apparatus according to claim 1 wherein theapparatus further comprises a wedge-shaped implant for disposition in awedge-shaped opening created in the tibia when the cut made along thecutting plane is opened.
 18. Apparatus according to claim 17 wherein thewedge-shaped implant comprises a plurality of components.
 19. Apparatusaccording to claim 17 wherein the wedge-shaped implant comprises aU-shaped construction when viewed from the top.
 20. Apparatus accordingto claim 17 wherein the wedge-shaped implant includes at least one keyfor disposition in a keyway disposed within the tibia.